Fluorothiacyl chlorides and polymers thereof



3,113,%6 rrnonorr-nacvr. cnrons'nrvn PGLYMERS rrmnnor I William E.Middieton, Ciayrnont, oer, assignor to n. r.

du Pont de Nenrours mil Company, Wilmington, Del, a corporation orDelaware No Drawing. Fitted Aug. 317, 1959, der. N 833,913

1 .Zll'flaims. (Cl. 260-79) This invention relates to, and has as itsprincipal obects provision of, novel thiocarbonyl compounds con-'taining both fiuorineand chlorine, polymers of these compounds, andmethods for the preparation of both the monomers and polymers.

. In accordance with this invention, there are now providedfluorothioacyl chlorides of the formula Y in which R isperfiuoroalkylene, preferably perfluoroalkyl one having 1-10oarbon'atoms, and X is fluorine, chlorine I or hydrogen. There are alsoprovided polymers'of the novel fluono'thioacyl chlorides. These polymersinclude the cyclic dimers as well as linear homopolymers and copolymersof these fiuorothioacylchlorides with other co- I polymerizablemonomers. least two recurring structural units of the formula Thesepolymers contain at wherein X and Rf have the meanings given above.

A general method for preparing the fluorothioacyl chlorides of thisinvention involves contacting a fiuorochloroalkane of the formula XR CYCl, wherein Y is chlorine,

bromine or iodine, and ;X and Rf have the meanings heretofore given,with sulfiur at a temperature. at which the sulfur is in vapor form. Atatmospheric pressure the reaction temperature is about 445 C;Temperatures be- -low 445 C. can be' used provided the pressure underwhich the reaction is carried out is lowered. Likewise, temperaturesabove 445 C. can be used provided the reaction pressure is raisedaccordingly. The reactionis conveniently carried' outinthe presence ofan inert gas,

e.g., nitrogen, and the volatile fluorothioacyl chloride is removed"from the reaction zone as soon as it is formed. It is convenientlycollected in a receiver cooled below the boiling point of thefluorothioacyl chloride, e.g., in a trap cooled by a mixture of solidcarbon dioxide and acetone.

One of the fiuorothioacyl chlorides of thisinvention, i.e.,trifluorothioacetyl chloride, can be prepared by contacting achlorofluoroalkyl mercury compound of the formula (CF CClZ) Hg, where Zis bromine or chlorine, with hot liquid or vapor of sulfur. The reactionis illustrated by the following equation:

'Preferably, the chlorofluoroalkyl mercury compound is introducedgradually into an excessgof refluxing sulfur under a'blanket of an inertgas, e.g., nitrogen, and the volatile ,fluorothioacyl chloride which isformed is collected in a receiver cooled to a temperature below theboiling point of the fiuonothioacyl chloride, e.g., in a trap cooled bya mixture of solid carbon dioxide and ace: tone. The product isolated inthe cold receiver can, if desired, be purified by fractionaldistillation.

' The reactionis conveniently carried out at atmospheric pressure at thetemperature-of refluxing sulfur, i.e., 445

C. Higher temperatures, and correspondingly higher pressures, canbe used:as long as the temperature, is below the decomposition temperature ofthe reactants or the products. Subatmospheric pressures, withcorrespondmgly lower temperatures, can also be employed if =desired. Thereaction between the chlorofluoroalkyl 'mercurycompound and the sulfurtakes place rapidly and the fluorothioacyl chloride reaction product isremoved from the reaction zone as it is formed.

The fiuoroalkyl mercury compounds used this process can be prepared byreaction of fluoroolefins of the formula ZCCI=CF wherein Z isbromine orchlorine, with mer curic fiuoride at an elevated temperature, e.g., C.,

optionally in the presence of a solvent for the mercuric fluoride, e.g.,hydrogen fluoride. The preparation offiuo- I roethyl mercury compoundsof this type is described in Us. Patent 2,844,614.

Another method for preparing the fluorothioacyl chlorides of thisinvention comprises the thermal decomposition of la chlorinatedfluOmaIkyI-LS-dithietane as illus- T trated by the following equation:

XRK s o1 A /C\ /C\ 2XRt fi Cl 01 s R.-X wherein X and Rf have themeanings defined previously; This decomposition is generally effected attemperatures between 450 and 700 C. The reaction is readily carried outby introducing the dithietane at a lowrate into aheated vessel,preferably a heated tube packed with an.

inert solid to effect uniform 'heat transfer, at reduced pressure. Thefluorothioacyl chloride thus produced is of high purity and is isolatedby passing the efiiuentreaction gases into a cold trap. Theisolatedproduct can be distilled if desired.

As indicated previously, the polymers of this invention includehomopolymers of the fluorothioacyl chlorides and also copolymers offiuorothio acyl chlorides with other co-epolymerizable monomers. Thesepolymers range from low molecular weight liquid polymers, i.e., dimers,trimers, and the like, to high molecular Weight solid polymers.

The polymers of this invention are prepared by polymerizing monomericfluorothioacyl chlorides of the formula XR CSlCl alone or in combinationwith one or more other copolymerizable monomers in the presence of 'anionic-initiator or in the presence of ultraviolet light.

The polymerization inthe presence of an ionic initiator can be carriedout at a temperature between 0 and C. or lower in the presence of asolvent such as an ether, e.g., diethyl ether or tetrahydro-furan, or ahydrocarbon,

e.g., pentane, that remains liquid at the operating temperature. Thepreferred temperature range for carrying out the polymerization isbetween -50 and 100- C. In

this temperature range diethyl ether is a particularly effeca.

Polymerization times range from a 'few tive solvent. minutes up toseveral days, e.g., 3-4 days, depending on the particular operatingconditions and the particular fiuorothioacyl chloride that is beingpolymerized.

A wide variety of ionic initiators can be used in this process. Specificinitiators that are operable includes amides, e.g., dimethylformamide,and N-methylacetamide; primary, secondary and tertiary amines, e.g.,triethylamine, diisopropylamine, N-methylmorpholine,tetra-'kis(dimethyIaminoJethylene, and nitrosodimeihylamine; phosphines, e.g.,triphenylphosphine; quaternary. ammonium chlorides having no hydrogen onthe quaternary ammonium nitrogen, e.g., tetraethyl quaternary ammoniumchloride; quaternary ammonium methoxide; alkali I metal fluorides, e.g.,cesium fluoride; and metal aslky ls, e.g., butyl lithium. Anionicinitiators, particularly d-imethylformarnide, are especially suitablefor making high molecular weight polymers. The ionic initiators can beemployed in concentrations ranging from about ().2% to 20% of the weightof the monomers being polymerized. Y

-ketones, e.g.,

preceding paragraphs.

The polymerization of the fluorothioacyl chlorides in the presence ofultraviolet light as the initiator is conveniently carried out in thepresence of an inert solvent such as highly halogenated hydrocarbon,e.g., dichlorodifiuoromethane. Any convenient source of ultravioletlight can be used. For example, any of the commercially available lampsthat are relatively high in ultraviolet output are suitable. Ge erallyspeaking, mercury vapor arc lamps are preferred since they provide arelatively intense source of ultraviolet light. Many lamps of this typeare available and they include low and high pressure lamps with varioustypes of envelopes. The most preferred are those with quartz envelopessince such envelopes permit the higher percent transmission ofultraviolet light.

The temperature and pressure at which the polymerization in the presenceof ultraviolet light is carried out are not critical. It is convenientto use room temperature and atmospheric pressure but lower or highertemperatures and lower or higher pressures can be used if desired. It isconvenient to carry out the polymerization at the boiling point of thesolvent being used. At ordinary temperatures and pressures thepolymerization is substantially complete in about one hour. However, thepolymerization can be continued for several hours, e.g., 6-8 hours, oreven more, if desired.

As indicated above, the polymers of this invention include copolymers offluorothioacyl chlorides With one or more other copoly-merizablemonomers. Preferably, the copolymers contain at least mole percent ofthe fluorothioacyl chloride. Examples of typical copolymerizablemonomers that can be used to prepare the polymers of this inventioninclude cthylenically unsaturated compounds that undergo vinyl typepolymerization, e.g., propylene, vinyl acetate, vinyl fluoride andtetrafluoroethylene; copolymerizable carbonyl and thiocarbonylcompounds, including thioacyl fluorides, e.g., thiocarbonyl difiuoride,triiluorothioacetyl fluoride; fiuorinated erfluorocyclobutanone; andr'luor-inated thioketones, e.g., periluorothioacetone. These comonomerscan be used in mixtures with fluorothioacyl chlorides in the desiredproportions and the mixtures subjected to the polymerizing conditionsdescribed in the Anionic initiators are especially effective inpreparing the copolymers of this invention.

The products of this invention and their preparation are illustrated infurther detail by the following examples.

EXAMPLE I T rifluorothz'oacetyl Chloride 445 C. i (0F3001mHg 28 F 001HgClz A reaction flask with two necks about 10" long and 1" in diametercontaining 150 g. of sulfur is heated until the sulfur refluxes up theneck for about 4". Through one of the necks 100 g. ofbis(1,l-dichlorotrifluoroethyl) mercury is added portion-Wise in a slowstream of nitrogen over a period of minutes. The other neck of the flaskis connected through an air condenser to a trap cooled by a mixture ofsolid carbon dioxide and acetone. After the addition is completed, thered condensate in the trap is distilled. There is obtained 21.7 g. oftrifiuorothioacetyl chloride as an intensely red liquid, 13.1. 28-29 C.

Analysis.Ca'lcd for C ClF sz 23.87%; F, 38.37%; S, 21.58%.

C, 16.17%; C1, Found: C, 16.11%;

The bis( 1,1dichlorotrifiuoroethyl)mercury is obtained in the shape offine, White needles, M.P. 180-185 C., on crystallization fromchloroform.

Analysis-Calcd for C F Cl llg: Cl, 28.10%. Found: Cl, 26.79%.

When bis(1bromo-lchlorotrifiuoroethyl)mcrcury is reacted with sulfurunder the conditions of Example I, trifluorothioacyl chloride is alsoobtained.

EXAMPLE I i 2Clzlorotetrafluorothiopropioizyl Chloride s l ClCFaCFzCClaClCFzCFsC-Ol A reaction flask fitted with two necks about 10" long and1" in diameter is charged with 100 g. of dry filtered sulfur. The flaskis flushed with nitrogen and heated until the sulfur refiuxes in theneck. There is then added 17 g. of1,1,gl,3-tetrachloro-2,2,3,3tetrafiuoropropane during 16 minutes. Thereis obtained 9.5 ml. of a deep rose-red liquid which on distillationyields 3 g. of an intense red liquid boiling at -93 C. and having arefractive index 11 of 1.4117. This product has the expected nuclearmagnetic resonance spectrum for 2- chlorotetrailuorothiopropionylchloride.

l Vhen the particular fiuorohaloalkane of Example ii is replaced by thespecific fluorohaloalkanes listed in column 1 of Table I and reactedwith sulfur under the conditions of Example 11, the specificfluorothioacyl chlorides listed in the second column of Table I areobtained.

TABLE I Fluorohaloalkane Fluorothioaeyl Chloride S ClCFzCFzCFzCFgCClaClCF2CFzCF3CFg( Cl S I-ICF CFZCCI: HCFQCF JCI S CFgBrCCl Br BrC Fzil- ClCFsCHClz CFzii-Cl EXAMPLE III Preparation of TrifluororlzioacetylChloride Dimer A solution of 8 g. of trifiuorothioacetyl chloride in 25ml. of dilluorodichloromethane is irradiated with ultraviolet light for2 hours. Most of the red color fades after 1 hour. At the completion ofthe 2-hour irradiation, the solvent is removed by evaporation and theresidue is distilled under reduced pressure. There is obtaincd 7.38 g.of 2,4-dichloro-2,4-bis(trifluoromethyl)-1, 3-dithietane as a colorlessliquid, 13.1. 66-68 C./25 mm, refractive index 12 1.4166. The nuclearmagnetic resonance spectrum obtained on this product indicates it to bea m'xture of the cis and trans isomers in the ratio of about 4: 1.

Analysis.-Calcd for C Cl F S C, 16.17%; 01, 23.87%; F, 38.37%; S,21.65%. Found: C, 16.90%; Cl, 23.80%; F, 38.33%; S, 20.93%.

EXAMPLE 1V Preparation of Poly (Triflzsorolhioacelyl Chloride) Qne dropof dimethylformarnide is added to a dilute solution of about 1 g. oftrifluorothioacetyl chloride in 10 ml. of dicthyl ether cooled to 78 C.After 30 minutes the reaction mixture is allowed to Warm to room Pmethyl)-2,4 dichloro-1,3-dithietane is over a'period of 30 minutes. Thered condensate in the at room temperature.

EXAMPLE v Preparation of 2,4-Bis(Chlorodifluoromethyl)-2,4- Y.Dichloro-l,3-Difl2ietane In a 250-ml. flask with two necks, each 15 cm.long, is placed 100 g. of sulfur. This is heated until it refluxes and148 g. of 1,1-dichloro-2,Z-difluoroethylene is passed into the reactionflask during the course of 2.75

hours. There is collected in a trap kept at room temperature, 130 g. ofproduct. The low-boiling traction obtained by distillation of the crudeproduct is unreacted starting material and small amounts of product arecollected along the way, but no flat is obtained until 73 75 C. at 10nan, where 28.1 g. is collected, 11

=1.4852. This is redistilled and 24.5 g. of 2,4-bis-(chlorodifluoromethyl) 2,4 dichloro v1,3 dithietane, coiling at 75-76C./9 mm. is collected.

Analysis.-Ca1lcd for C F Cl S C, 14.6%; F, 23.0%; Cl, 43.0%; S, 19.4%.Found: C, 14.6%; F, 23.2%; C1,

EXAMPLE, V-I

Preparation of Chlorodifiuorothioacetyl Chloride A 2.5 cm. tubeof theheat-resistant glass known corn- 'morically as Vycor, packed for alength of 25 cm. with quartz rings, is connected to a trap cooled bysolid car- 7 hon dioxide-acetone and the system is evacuated to 1 Hgpressure with an oil pump. The packed tube is heated to 600 C. and l g.of 2,4-bis(chlorodifluoroadded dropwise trap is distilled under reducedpressure. There is obtained 8.1 g. of chlorodifiuorothioacetyl chlorideas a deep red l-iquid, B1. ca. 10 C./ mum, 11 -=1.4465

Analysis.Ca 1cd for C Cl F S: C, 14.56%; Cl, 42.98%; F, 23.03%; S,19.40%. Found: C, 14.71%; Cl,43.12%; F, 23.02%; S, 19.37%.

EXAMPLE vn Poly'(Chlorodifluorothioacetyl Chloride) A solution of 4.0 g.of chlorodifluorothioacetytl chloride in 20 ml. of dry diethyl ether iscooled to 78 (3., and one drop of dimethylformamide is added. Thesolution is allowed to remain zit-78 C. for 4 hours. After this time,most of the red color has faded. Methanol is added to precipitate thepolymer, and the polymer is washed with methanol and drie-d'in vacuo. Atough, white, flexible film is pressed from the polymer at 80 C. and10,000 lbL/sq. in.

Analysis.Calcd for (C Cl F S) C, 14.56%; Cl, 42.98%; F, 23.03%; S,19.40%. Found: C, 14.92%; Cl, 42.97%; F, 23.79%; S, 19.79%.

The monomeric fluorothioacyl chlorides of this invention are useful invarious applications. For example, they are particularly useful asinsecticides and fumigants.

' For example, trifiuorothioacetyl chloride is especially efreactive.For example, they react with alcohols to form thiol esters.

The monomeric fiuo rothioacyl chlorides of this invention possess theoutstanding advantage over the hitherto known thiocarbonyl compounds ofbeing extremely stable to storage at room temperature in the absence oflight. In contrast, thiobenzoyl chloride polymerizes on storagePolyfluorothioketones are stabie at temperatures'of about 80 C. for onlyshort periods of time, and a-fluorothioacyi fluorides polymerize i i afew days when stored at 25 C.

The polymeric fluorothioacyl chlorides of this illVfiII- tion are alsouseful in a variety of applications. The dimers are particularly usefulas dielectric liquids and solvents for the higher molecular weightpolymers. The

dimers are also useful for thermal cracking to monomeric fluorotlhioacylchlorides of high purity. The higher molecular weight polymers offluorothioacyl chlorides are useful as adhesives and coatingcompositions. They are particularly useful as adhesives in joiningsheets of paper together. Still higher molecular weight polymershydrogen fluoride and to burning. V

Since obvious modifications and equivalents in the'invention will beevident to those skilled in the chemical arts, I propose to be boundsolely by the appended claims. I

The embodiments of the invention in which an exclusive property orprivilege is claimed are definedfas follows.

I claim:

1. A iluorothioacyl chloride of the formula wherein R, isperfluoroal-kylene of up to IO carbonsa'nd X is a member of the groupconsisting of fluorine, chlov rine and hydrogen.

2. Trifiuorothioacetyl chloride. 3. Chlorodifiuorothioacetyl chloride. V4. The process of preparing tri-fluorothioacetyl chloride whichcomprises reacting a precursor of the formula (CF C-ClZ) 1-Ig, wherein Zis selected from the group consisting of bromine and chlorine,withsulfur at elevated temperature.

5. The process of preparing trifiuorothioacetyl chloride which comprisesreacting bis(l,lsdichlorotrifluoroethyhmercury with sulfur at elevatedtemperature. I

6. The process of preparing a compound of claim 1 which comprisesthermally decomposing a chlorinated iluoroalkyl-1,3-dithietane atelevated temperature.

7. The process of preparing chlorodifluorothioacetyl chloride whichcomprises thermally decomposing 2,4-'

bis(chlorodifiuoromethyl) 2,4 dichloro 1,3 dithieta'ne at elevatedtemperature.

8. A homopolymer of a compound of claim 1. "9. A solid, linear copolymerof a compound of claim 1 and at least one other copolymerizable monomer.

10. A dimer of a compound of claim 1. 11. Poly(trifluorothioacetylchloride).

12. 2,4 his(trifiuoromethyl) 2,4 dichloro 1,3-

dithietane.

13. Poly(chlorodifiuorothioacetyl chloride). I

14. The polymer of claim 8 in the form of a shapedstructure.

v 15. The process of dimerizing a compound of claim 1 18. The process ofclaim 17 accomplished in the presence of a second copolymerizablemonomer. I

19. The process of polymerizing trifluorothioacetyl chloride whichcomprises contacting the same in' a liquid solvent with an ionicinitiator at a temperature'of about 0 to C. p

20. The process of polymerizing chloro'difiuor'othioa-cetyl chloridewhich comprises contacting the same in a liquid solvent with an ionicinitiator at a temperature of about 0 to -120 C.

are useful in preparing molded objects and films that are resistant to"I: 21. A self-supporting film formed from p01y(chlorodifiuorothioacetylchloride).

References Cited in the fils of this patent UNITED STATES PATENTSHaworth et a1 Aug. 30, 1949 Waters et a1 July 28, 1953 Cushing Oct. 11,1955 Nickerson Sept. 9, 1958 OTHER REFERENCES Chemical Abstracts, Vol.30, page 693, abstracting Delepine at 211., Bull. Soc. Chinm, 512,1969-80 (1935).

11. POLY(TRIFLUOROTHIOACETYL CHLORIDE).